Range finder



June 4, 1946. M'IHALYI ET AL 2,401,709

RANGE FINDER Filed Jan. 19, 1943 4 Sheets-Sheet l JOSEPH MIHALYI' FORDYCE E .TU TTLE INVENTORS BY m",

Ju 1946- 'J. MIHALYI ETAL RANGE F I NDER Filed Jan. 19, 1943 4Sheets-Sheet 2 JOSEPH MIHALYI T. G Wm M A UT & N ,Y EW w Gm A W 1 m F YB June 4, MIHALY' ETAL RANGE FINDER Filed Jan. 19, 1945 I 4 Sheets-Sheet4 FIG. 8A.

FIG. 9.

FIG. 8

N JOSEPH MIHALYI FORDYCE E. TUTTLE' g INVENTORS Mount for optical elemnt Patented June 4, 1946 UNITED STATES PATENT OFFICE RANGE FINDER JosephMihalyi and Fordyce Tuttle, Rochester, N. Y., assignors to Eastman KodakCompany, Rochester, N. Y., a corporation of New Jersey ApplicationJanuary 19, 1943, Serial No. 472,835

- Serial Title N 0. Filed Inventors 461, 584 Oct.

461, 585 Oct.

491, 954 June 23, 1943 491, 955 June 23, 1943 491, 956 June 23, 1943505, 016 Oct. 5,1943

Mihalyi.

Do. Do.

Do. Mihalyi, MacNeille. Mihalyi.

e Range finder construction.

Range finders-Case A. Range finders-Case B Range findersase O Rangefinders-Case D. Range finders-Case F Range finders0ase G. Range finders-Case H. Range finders-Oase L. Range finders-Case 1.. Range findersCaseK- Range finders-Case L Polarizing beam splitter. Range finders-Gase M.Range finders-Case N. Range finders-Case O Range finders-Case P Do.Holmes, Mihalyi.

' Mihalyi, MacNeille. MacNeille, Holmes. Mihalyi, MacNeille. Mihalyi.

1, 1943 MaeNeille.

Do. MacNeille, Mihalyi. MacNeille. MacNeille, Mihalyi.

Cases A, B, and C describe auto collimating range finders in which animage of one adjustment coindicant element is projected adjacent to theother, the element light beam passing through the range finder opticalsystem to compensate for any maladjustment therein.

The present Case E has for its object the expansion of the range scaleor more exactly, the conversion of the small displacement of the indexto a large easily controlled movement of some movable member. Thispermits the use of either a greatly expanded scale or, what is theequivalent thereof, a direct mechanical coupling to a director such asused in timing fuses in anti-aircraft fire. The object of one embodimentof the present invention is to provide this large movement in a formuseable with the prevalent types of directors.

These objects of the invention are obtained by substituting for thescale and index specified in cases A, B, and C of this series, acoincidence: line and fiducial mark arranged to operate approximately atright angles to the direction of deviation of the element light beam.The image of one of these is projected through the optical system of arange finder as described in the other cases of the series into focusforming an image adjacent to the other element (or possibly an image ofthe other element). The coincidence line is carried, or more generallyboth elements are carried, on a movable member Which is moved to bringthe line and mark into coincidence as indicated by superposition of theele- 22 Claims. (Cl. 882.7)

. 2 ment image and theadjacent other element. If, for example, due tothe adjustment of the instrument the fiducial mark is moved slightly ina direction which for convenience We shall refer to as horizontal, .thecoincidence line which is not quite vertical is then moved in a verticaldirection a relatively" great distance until it is brought intocoincidence with the fiducial mark image.

Of course, in certain forms of the invention, the terms coincidence lineand fiducial mark are interchangeable relative to the elementsespecially if both elements are carried on the movable member, but at,least one element must be so mounted and this one can always be referredto as the coincidence line. The member carrying the coincidence line ismovable at only a slight angle to the line so that a large movementproduces only a small eifective shift of the line.

linear at a slight angle thereto or the line may be spiral, (fiat orhelical) and the movement circular so that the slight angle in questionis between the tangents to the spiral and to the corresponding circlerespectively.

In one embodiment of the invention the movable member operates a'scaleand index by moving one relative to the other, for example, by carryinga scale which is read against a fixed index. Preferably the coincidenceline is so curved that the degree of movement of the movable supportingmember is linear with respect to the range. Such an arrangement permitsdirect coupling into standard forms of directors;

mex min) A m I 1' BF where r is the radius to the point on the spiral, Ais the angle to. the point on the spiral, R is the range, B is the baselength, and F is the objective focal length.

Many range finders have what is called a halving adjuster. These deviceswhich often are run! simple tilting blocks of glass are used to moveimage of one of these marks is projected with the adjacent adjustmentcoindicant element to form an image which is in elevation coincidencewith the other halving indicating'mark when the halving adjustment isproper. Thus, while a reading is being taken, there is a directindicainto the range finder system by another small penta prism 21cemented to the other viewing point penta prism ll whence it is focusedby the objective l2 and enters the prism [3 but instead of beingreflected into the right angle prism l6, it enters an auxiliary prism 28cemented to the hypotenuse surface of the prism 13. This element beam isbrought to focus forming an image 2!! of the fiducial mark on a disk 30which rotates about a pivot 31. The disk 30 carries a spiral 32 whichoperates as a coincidence line for the fiducial mark image 29? whenobserved through the eyepiece 34 by the eye 33 of a coincidenceobserver. *The coincidence observer rotion of the halving adjustment andit may be 7 corrected if improper.

Even when other forms of range indicatingele ments are used, thesehalving indicating marks are useful, since they give easy, exact andsimple indication of the halving adjustment.

.flhe'details of the invention and further objects and advantagesthereof will be understood from the following description when read inconnection with. the. accompanying 'drawings, in which:

Fig. 1 is a perspective view of'the optical system of one embodiment ofthe invention;

'Fig. 2 is a plan view ofa range finder incorporating the optical systemof Fig. 1;

Fig. 3 is a perspective view of the optical system of Ta preferredembodiment of the invention, Figs. SAand 3B showing'the views throughthe eyepieces of the instrument; Y 7

Fig; 4. shows one detail of the embodiment shown in Fig. 3; V I

Fig. 5 is a plan view by range finder incorporating the optical systemshown in Fig. 3;

' Fig. 6 showsan alternativeform' of one detail ofthe system shown inFig; 3;

Fig. 7 is a perspective view of another embodiment of the invention;

Fig. 8 illustrates the application of the invention to a stereo rangefinder, Fig. 8A showing the field of view through the binoculareyepie'e'es and Fig. 83 showing the fieldthrough'the range readingeyepiece;

Fig. 9 is a plan view of a range finder incorporating the optical systemshown in Fig. 8;

Fig; 10 illustrates still another embodiment of the invention.

In Figs. land 2 two light beams from the object being ranged arereceived by pentaprisms I anddirected through objectives l2 towardcrossed prisms l3 and i4 and after reflection are brought into focus ina comparison field. These beams are reflected by the crossed prisms l3and I4 into two right angle prisms l6 and I! whose interface has twoportions one of which, I8, is transmitting and the other of which, I9,is reflecting. A light passes through a fiducial mark which consists ofa transparent area in the reflector l9 and forms an element beam whichpasses in turn through the halving adjuster 43, an objective l2 to becolliinated thereby, a penta' prism .li, a small pentaprism Z6 cementedthereto and then from one viewing .point to the other to bedirected'back tatesthe disk 36 until the spiral 32 overlaps the image 2%exactly. At this time, the range is'read by a third observer whose eyeappears at, 31 through an eyepiece 38 focused on an index 36 i2 and d4extend to permit operation respectively of the light deviating means 45andthe halving adjuster 41%. These Figs. '1 and 2 are mainly toillustrate the principle of the invention broken into its componentparts,,but more preferable embodiments require fewer observers orhavefiducial marks coupled to the coincidence" line.

Fig. 3 differs from Fig. 1 by having the fiducial mark mounted on thesamerotating memberas the coincidence line. In Fig; '3 the coincidenceline is the adjustment coindicantielement projected, only part of itbeingprojected at any one time of course; Light from a lamp 50 isreflected by a, totally reflecting prism 5| through a transparent spiral52 carried' on a disk 53 mounted to rotate about a pivot 54. This lightenters a rhomb 55 and then by means of a small prism 56 cemerited to thehypotenuse surface of the prism.

it enters the rangefinder optical system to begin the round'trip comingout again at the prism 28 to enter another rhomb '5'! and to come tofocus forming an image 52' adjacent to a circle 60 carriedconcentrically by the disk 53. The circle 60 constitutesthe'fiducial'mark in this case. convenience. in reading coincidence. asmall disk is provided adjacent to the circle having masked off portionst! accurately aligned on the circle 60. As shown in Fig. 3B the image52' of the spiral 52 in general appears to one side of the circle 60.Rotation of the disk 53 will bring into the field of view that portionof the spiral 52 whose image 52 exactly overlaps th circle 60, i. e. isin coincidence therewith. By means of a relay objective 63, an

enlarged image of this disk appears at 62 to be viewed'through aneyepiece 84 by the eye 65 of an observer. The range is read by index 53and scale 59.-

In Fig. 4; the disk is shown with the spiral '52 so curved that equalangles of rotation of the disk 53 correspond to equal incrementsof-range'indicated on the scale 59;

Fig. 5 shows this same instrument in a housing As shown in this figure,the coincidence of. r the object images may be adjusted by moving thecrossed prisms i3 and M transversely with respect to the base of therange finder. This transverse movement is provided by mounting the prismunit in a support 12 which is urged by A second knob i5 is provided onthe pivot 54 to rotate the disk carrying the coincidence line andfiducial mark' Fig. 6 illustrates a simplified device which may For thelight from the lamp 50 afterbeing reflected.

by the prism 5| passes through a transparent fiducial mark 8I which inthis case is a straight: line; The coincidence line 82 is also 'astraight line at a slight angle to the mark 8| so that they tend toconverge which'is, of course, the equivalent to the circle and spiralsystem of Fig. 3; The member 80 carrying both the flducial mark andcoincidence line is moved linearly until coincidenge is reached at whichtime the range may be read by a scale 83 against an index 84.

In Fig. '1 the invention is applied to a single objective range finderin which the object beams are reflected respectively by a mirror 90 anda semi-transparent mirror 9I through an objective 92 and an erectingprism 93 into focus on a disk 94. The object images are viewed throughan eyepiece 95 by the eye 96" of an observer. Coincidenceis provided byrotating the mirror 90 by means of a supporting nut 91 and driving screw98. Light from a lamp I is reflected by a total reflecting prism IOIthrough a transparent circle I02 mounted on a rotatable disk I03 toconstitute a fiducial mark. The element beam from this mark I02 passesthrough the erecting prism 93, the objective 92' and is reflected firstby the front surface I06 of a, prism cemented to the mirror 90' and,second, by a dove prism I04 cemented to the semi-transparent mirror 9|.This beam is then focused by the objective 92 to form an image I02 onthe disk 94 whereat it is matched by a coincidence line in the form ofspiral I05 also mounted'on the disk I03. In the embodiment shown, therange is read by a scale H0 carried by the disk I03, against an indexIII when the disk I03 is rotated to give coincidence between the spiralI05 and image I02. .Alternatively the scale could be engraved adjacentto the spiral to be read directly through the eye-piece 95 or adjacentto the circle I02 so that the image of the scale would be projectedtherewith to appear adjacent to the line image I02 and again to be readthrough the eyepiece 95. Similarly, the equivalent system in which noscale is read but in which the setting of the disk I03 is fed directlyby mechanical coupling such as spur gears into a director or timer, maybe used.

In Fig. 8 the inventionis applied to a stereoscopic range finder inwhich the object being ranged is represented by two small aeroplanesI30. Light from this object passes through front windows I3I and isreflected by optical squares I32 through objectives I33 forming imagesin the image planes I34. By means of relay lenses I40, erecting prismsI4I, rhombs I42 for adjusting for I interpupillary separationand'eyepieces I43 these images are viewed stereoscopically by the rightand left eyes I44 of an observer. The images I30 as seen in Fig. 8A areviewed stereoscopically to give an apparent object distance" which canbe varied by adjusting a light deviating means I46 (by a knob I 49 shownin Fig. 9) until this apparent object distance appears the same as theapparent reticle mark distance or" two reticle marks I35 engraved 'onthe image planes I34.

eye I23 of an observer.

one window vicinity to the other whereat it strikes an auxiliarypenta'prism I53 and reenters the optical system of the range finder.This element beam is focused by the right viewing point objective I33(which appears to the left of the Fig. 8) in the optical equivalent ofthe right eye focalplane I34. For convenience a reflector I54 iscementedto thisfocal plane to reflect this element beam upwards so thatthis image appears at I61 adjacent to a coincidence line I59 carried bya disk I59 which is rotatable about a pivot I60. To eliminate anyunwanted lateral movement between the disk I56 and the image I61,

this pivot I60 is carried by transparent member I55 which is alsocemented to the focal plane I34. Thus, any lateral movement of thepivotI60 is accompanied by an equivalent movement of the reticle mark I35. Bymeans of an optical system I51 including a relay lens, erecting prismsand an eyepiece, this image I61 and the coincidence line I59 are viewedby the eye I50 of an auxiliary observer. In practice, the primaryobserver I44 adjusts the light deviating means I 46 until the apparentobject and reticle mark distances are the same and the auxiliaryobserver I58 rotates the disk I56 until the flducial mark' image I61 andcoincidence mark I59 arein coincidence. At

this time, the auxiliary observer may read a scale I69 engraved adjacentto the coincidence line I59, against an index I68 which may either beengraved on an auxiliary disk I6I forming part of the relay system I 51or may be engraved adjacent to the fiducial mark near the prism I5I tobe projected therewith. I i f I In any case, it is preferable to have ahalving.

Fig. 9 shows all of this optical system mounted in a housing I10. 5

Fig. 10 shows a somewhat different embodiment of the invention in whichthe object beams are received by penta prisms H5 and reflected bycrossed mirrors I20 through a single objective I2I to form images in thefocal plane of an eyepiece I22 through which they are viewed by the Inthis illustration the sliding member is shown for convenience and lightfrom the flducial mark iscollimated by an auxiliary objective I25 and isreflected by the backs of the mirrors I20 around the optical system andfrom one viewing point to the other by 1 auxiliary penta prisms II6which are provided our invention, we wish to point out that it is notlimited to these structures, but is of the scope of the appended claims.

What we claim and desire to secure by Letters Patent of the UnitedStates is:

1. A range finder of the type having adjustment coindicant elementsindicative of adjustment in the ranging plane and means for projectingthrough .at least part of the optical system. of: the finder, light fromone" element into focus forming. an image adjacent to at least an. imageof the other element, said range finder "member which is movable in adirection at a slight angle to said line for bringing said element.image and said other element into coincidence.

--2. A range finder of the type having two spaced viewing points atwhich. substantially collimated beams of light are received from theobject being ranged, an optical system including at, least one objectivefor directing the two collimated" beams into focus forming images incomparison planes, oneportion of the optical system operating only onone of the beams and another portion operating only on the other beam,and a ranging adjuster, said finder being characterized bya fiducialmark and a coincidence line constituting adjustment coindicant elements,said coincidence line being carried by a movable member which is movablein a direction at a slight angle to said line and means for projectingthrough at least the exact optical equivalent of both of said portions,light from at: least one of the elements into focus forming an image of.said one element adjacent to at,

least an image of the other element, said rangving adjuster alsoadjusting said one element,

image. I

3. A range finder according to claim 2 in which said movable membermoves a-scale and index relative to one another.

'7. A ranger finder according to. claim 2 in which the elements .areconverging lines both carried by. said movable member;

8. A range finder according to claim 2 in which thejmark and the lineare converging lines I both carried by the movable member and said'member is movable parallel to the mark.

9. A range finder according to claim 2. in which the mark and line areconverging lines both carried by the movable member, saidmark being astraight line and said movable member being movable parallel to the.mark.

10. A range finder according to claim 2 in which the fiducial mark -is acircle, the coincidence line is a spiral and the movable member carriesboth and is rotatable'about a line perpendicularly through the center ofthe circle.

11. A range finder according to claim 2, in which the fiducial markisacircle, the coincidence" line is a fiatspiral and the movable member isflat, carries both'themark and the line and is pivoted concentricallywith the'circle. 12. 1 5. range finder according; to! claim 2 in whichthe fiducial mark is a circle, the coincidence line iSQE t spiral andthe movable mem- 8T ber .carries' both and is rotatable about a line:-perpendicularly through the center of the circle,

said spiral being curved to make the angular rotation ofthe memberlinear withrespect torange; P

13.'A coincidence range finder of the type having means for aligninglight beams from two spaced viewing points, adjustment coindicantelements indicative of adjustment inthe ranging plane andintegrally'attached to one anotherand means for projecting through atleast the equivalent of all of'said aligning meanslight from one elementinto focus forming an, image adjacent to the other element, saidrange'finder being characterized by one ofsaid elementsbeing a fiducialmark .and the other being a concidence line, both elements being-linesapproximately effectively'at right angles tothe'ranging plane and on amember movable in the direction of the. fiducial mark'and said linesbeing converging. Y

14. A ranger finder according to claim 13 in which both lines arestraight.

15. A range finder according to claim 13 in which the fiducial mark is'aci1cle,vthe coincidence'line is a spiraland the movable member carriesboth and is rotatable about a line perpendicularly through the center ofthe circle 16.. A :range finder according to claim 13 in which thefiducial mark is a, circle, the coincidence line is a flat piral and themovable member is flat, carries both the mark and the 7 line and ispivoted concentrically with the circle.

1'7. A ranger finder according to claim '13 in which the fiducial markis a circle,;the coincidence line i a spiral and the movable member'carries .both and is rotatable. about. a line perpendicularly throughthe center, of the circle,- said spiral being. curved to make theangular rotation of the'member linear with respect to range. I

18. 'A ranger finder according to claim 13 in which said movable membermoves apscale an indexrelative-to one'another.

. 19. A ranger finder according to claim 13 in which saidcoincidencelineis curved to make the degree of movement of said movable member 7relative position of the object images in elevation and having adjacentto the elements halving indicating marks, the image of one of whichbeing in elevation coincidence with. the other only when the halvingadjustment is proper.

21; A range. finder. according to claim 13 including a halving. adjusterfor adjusting the relative position of they object imagesin eleva tionand having adjacent to the elements halve ing indicating; marks, theimage of one of which beingin elevation coincidence with the other;

only when the halving adjustment iswproper.

22. In a rangefinder having" a halving adjuster and autocollimatingmeans'for projecting through at least part of-its optical system animage-of one adjustment coindicant element ad-, jacent to at leastan-image, of another element, the subcombina-tion which. consists of-ahalving indicating mark :adjacentto each of the elements, the image ofone .of. the marks as projectedadjacentto'at least an image of the othermark by said projecting means being in elevation coincidence with theother mark onlywhen thehalving adjustment is proper. I

, JOSEPH.,MIHALYI.

FORDYCE

